いい加減読もうよ
ビタミンミネラル良質の脂質等を排除するよう努めたサプリメントが、所謂プロテインパウダー
仮にヴィーガンが肉や魚の代わりにプロテインシェイクを摂取しても、栄養の代替にはなり得ない

Incomplete Nutrition
Protein shakes are designed to be heavy on protein, but that means they often fail at providing significant amounts of carbohydrates, vitamins, minerals and healthy fats.
Even if a commercial protein shake or supplement is fortified, it won’t offer the same kind or level of nutrition as whole foods.
According to Mayo Clinic physicians, whole foods always have the benefit over supplement products such as shakes, because they contain naturally occurring fiber, antioxidants, phytochemicals and other protective substances that can’t be reproduced.

Sustainability Issues
…You may develop nutrient deficiencies if you replace too many meals with shakes or you could regain the weight you had lost after you return to your previous eating habits.

http://healthyeating.sfgate.com/disadvantages-protein-shakes-7305.html